package dtst;

public class MyLinkedList {
    static class ListNode {
        public int val;
        public ListNode next;
        public ListNode prev;
        public ListNode(int val){
            this.val=val;
        }
    }
    public ListNode head;
    public ListNode last;


    //头插法
    public void addFirst(int data){
        ListNode node=new ListNode(data);
        if(this.head==null) {
            this.head=node;
            this.last=node;
            return;
        }
        node.next=this.head;
        this.head.prev=node;
        this.head=node;
    }
    //尾插法
    public void addLast(int data){
        ListNode node=new ListNode(data);
        if(this.head==null) {
            this.head=node;
            this.last=node;
            return;
        }
        last.next=node;
        node.prev=last;
        node=last;

    }
    //任意位置插入,第一个数据节点为0号下标
    public void addIndex(int index,int data){
        if (index<0||index>size()) {
            System.out.println("输入下标不合法");
            return;
        }
        if (index==0) {
            addFirst(data);
        }
        if (index==size()) {
            addLast(data);
        }
        ListNode node=new ListNode(data);
        ListNode cur=findIndex(index);
        node.next=cur;
        node.prev=cur.prev;
        cur.prev.next=node;
        cur.prev=node;
    }
    private ListNode findIndex(int index) {
        ListNode cur=this.head;
        while (index!=0) {
            cur=cur.next;
            index--;
        }
        return cur;
    }
    //查找是否包含关键字key是否在单链表当中
    public boolean contains(int key){
        ListNode cur=head;
        while (cur!=null) {
            if(cur.val==key) {
                return true;
            }
            cur=cur.next;
        }
        return false;
    }
    //删除第一次出现关键字为key的节点
    public void remove(int key){
        ListNode cur=head;
        while (cur!=null) {
            if (cur.val==key) {
                if (cur==head) {
                    head=head.next;
                    if (head!=null) {
                        head.prev=null;
                    }
                }else {
                cur.prev.next=cur.next;
                if (cur.next==null) {
                    last=cur.prev;
                }else {
                    cur.next.prev=cur.prev;
                }
                    }
                return;
            }
            cur=cur.next;
        }
        System.out.println("没找到该数字");
    }
    //删除所有值为key的节点
    public void removeAllKey(int key){
        ListNode cur=head;
        while (cur!=null) {
            if (cur.val==key) {
                if (cur==head) {
                   head=head.next;
                   if (head!=null) {
                       head.prev=null;
                   }else {
                       last=null;
                   }
                }else {
                    cur.prev.next=cur.next;
                    if(cur.next==null){
                        last=cur.prev;
                    }else {
                        cur.next.prev=cur.prev;
                    }
                }
            }
                cur=cur.next;
        }
    }
    //得到单链表的长度
    public int size(){
        int count=0;
        ListNode cur=this.head;
        while (cur!=null) {
            cur=cur.next;
            count++;
        }
        return count;
    }
    public void display(){
        ListNode cur=this.head;
        while (cur!=null) {
            System.out.print(cur.val+" ");
            cur=cur.next;
        }
    }
    public void clear(){
        ListNode cur=head;
        while (cur!=null) {
            ListNode curNext=cur.next;
            cur.next=null;
            cur.prev=null;
            cur=curNext;
        }
    }
}
